📄 rfc3149.txt
字号:
Network Working Group A. Srinath
Request for Comments: 3149 G. Levendel
Category: Informational K. Fritz
Sylantro Systems
R. Kalyanaram
Wipro Systems
September 2001
MGCP Business Phone Packages
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2001). All Rights Reserved.
Abstract
This document describes a collection of MGCP (Media Gateway Control
Protocol) packages that can be used to take advantage of the feature
keys and displays on digital business phones and IP-Phones.
IESG Note
This document is being published for the information of the
community. It describes a non-IETF protocol that is currently being
deployed in a number of products. Implementers should be aware that
the IETF Megaco working group and the ITU-T Study Group 16 have
produced a standards track RFC "Megaco Protocol Version 1.0" (RFC
3015, also published as ITU recommendation H.248) which addresses the
same problem space and are developing extensions to that protocol for
functions of this type.
Table of Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 General Information. . . . . . . . . . . . . . . . . . 4
1.2 Objectives . . . . . . . . . . . . . . . . . . . . . . 5
2. MGCP Packages for Business Phones . . . . . . . . . . . . . 5
2.1 Feature Key Package. . . . . . . . . . . . . . . . . . 6
2.2 Business Phone Package . . . . . . . . . . . . . . . . 9
2.3 Display XML Package. . . . . . . . . . . . . . . . . . 9
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RFC 3149 MGCP Business Phone Packages September 2001
3. Endpoint Naming and Phone Type Determination. . . . . . . .10
4. Functions that should be Locally Implemented. . . . . . . .11
4.1 Volume Control . . . . . . . . . . . . . . . . . . . .11
4.2 Audio Path . . . . . . . . . . . . . . . . . . . . . .11
4.3 Microphone mute button and light . . . . . . . . . . .11
5. XML Package Support . . . . . . . . . . . . . . . . . . . .12
5.1 XML Documents. . . . . . . . . . . . . . . . . . . . .12
5.2 XML Requests . . . . . . . . . . . . . . . . . . . . .13
5.3 XML Request History. . . . . . . . . . . . . . . . . .15
5.4 XML Events . . . . . . . . . . . . . . . . . . . . . .15
5.5 XML Tags . . . . . . . . . . . . . . . . . . . . . . .15
5.5.1 XML Tag. . . . . . . . . . . . . . . . . . . . . . .17
5.5.2 Card Tag . . . . . . . . . . . . . . . . . . . . . .18
5.5.3 P Tag. . . . . . . . . . . . . . . . . . . . . . . .18
5.5.4 Select Tag . . . . . . . . . . . . . . . . . . . . .18
5.5.5 Option Tag . . . . . . . . . . . . . . . . . . . . .19
5.5.6 Input Tag. . . . . . . . . . . . . . . . . . . . . .20
5.5.7 Echo Tag . . . . . . . . . . . . . . . . . . . . . .20
5.5.8 Calltimer Tag. . . . . . . . . . . . . . . . . . . .21
5.5.9 Time Tag . . . . . . . . . . . . . . . . . . . . . .21
5.5.10 Timer Tag . . . . . . . . . . . . . . . . . . . . .21
5.5.11 Do Tag. . . . . . . . . . . . . . . . . . . . . . .22
5.5.12 Go Tag. . . . . . . . . . . . . . . . . . . . . . .22
5.5.13 Prev Tag. . . . . . . . . . . . . . . . . . . . . .23
6. Security Considerations . . . . . . . . . . . . . . . . . .23
7. Acknowledgements. . . . . . . . . . . . . . . . . . . . . .23
8. References. . . . . . . . . . . . . . . . . . . . . . . . .23
9. Authors' Addresses. . . . . . . . . . . . . . . . . . . . .24
Appendix A: BNF description of XML grammar . . . . . . . . . .25
Appendix B: Sample XML Documents, Renderings and Events. . . .27
B.1 Sample Deck 1 (Itemized List Box). . . . . . . . . . .27
B.2 Sample Deck 2 (Enumerated List Box). . . . . . . . . .28
B.3 Sample Deck 3 (Text Box) . . . . . . . . . . . . . . .29
B.4 Sample Deck 4 (Echo Box) . . . . . . . . . . . . . . .30
B.5 Sample Deck 5 (Input Box). . . . . . . . . . . . . . .31
B.6 Sample Deck 6 (Timers) . . . . . . . . . . . . . . . .32
Appendix C: Example usage of MGCP extension packages . . . . .33
C.1 Setting Labels on Phone. . . . . . . . . . . . . . . .33
C.2 Activating a Feature on a Feature Key. . . . . . . . .33
C.3 Generating a Call using Feature Key as a Line Key. . .35
C.4 Determining Make and Model of a Phone. . . . . . . . .38
Appendix D: BNF Description of X-UA Parameter. . . . . . . . .39
Full Copyright Statement . . . . . . . . . . . . . . . . . . .41
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RFC 3149 MGCP Business Phone Packages September 2001
1. Introduction
The Media Gateway Control Protocol (MGCP) Version 1.0 defines a
protocol for controlling Voice over IP Telephony Gateways from
external call control elements. As defined, it supports external
call control elements called Media Gateway Controllers and assumes
that these Gateways can support collections of endpoints. The
endpoint type known as an "analog line" can be used as a client
interface to provide service to a basic analog telephone unit. The
packages that are currently defined to handle events and signals
allow for only a basic level of audio connection and signaling to
such endpoints. To handle more advanced capabilities commonly found
on business phones such as feature keys, speaker phones and displays,
it is necessary to define additional packages as extensions to the
MGCP protocol.
These packages, when used in conjunction with the packages currently
defined in RFC 2705 (Media Gateway Control Protocol Version 1.0) [1],
allow an MGCP Call Agent to control business phone endpoints.
The MGCP extension packages defined here are as follows:
- Feature Key Package
o Groups events and signals associated with the additional
keys available on business phones that are non-DTMF and not
locally-implemented. These include:
- Feature Key event to allow mapping of key numbers to
features.
- Key State signal to indicate the state of feature keys.
- Set Label signal to display a label on the LCD next to a
feature key.
- Business Phone Package
o Groups signals that are not related to feature keys,
including:
- Force Off-hook and Force On-hook signals to allow
application integration with speaker phone capabilities.
- Beep signal to play a beep on the phone.
- Display XML Package
o Used to convey XML [2] script data to and from the phone to
control the display and assign functions to the display
soft-keys for event reporting. These include:
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- XML event to report user input or selection.
- XML signal to render text to the LCD display.
An MGCP experimental parameter is also defined here:
- User Agent Parameter
o Used to determine the make and model of a phone
1.1 General Information
A generic business phone typically includes a number of features that
provide access to additional functionality useful in a business
environment. Beyond the basic handset and dial pad, a business phone
may optionally include a number of fixed buttons, line keys and
programmable feature keys, along with an LCD display and soft-keys.
Specific examples of items that may be included on a business phone
are:
- Speaker phone microphone and speaker
- Speaker phone button and light
- Messages button and light
- Redial button
- Volume up and down buttons
- Hold button and light
- Transfer button and light
- Forward button and light
- Conference button and light
- Microphone mute button and light
- Multiple feature keys with lights
- Multi-line LCD Display
- Multiple soft-keys next to the LCD display
- Navigation keys
Examples of fixed buttons functionality are 'hold', 'transfer',
'redial', 'conference', 'call-logs', 'directories', and 'messages'.
Fixed buttons may vary from phone to phone. While the packages
described here would allow these to be reported to a Call Agent, the
Call Agent would also need to determine which feature key number
corresponds to a particular pre-assigned function.
Since MGCP assumes a call control architecture where the call control
"intelligence" is outside the Gateways and handled by external call
control elements, the programming of the feature keys would be
resident in the Call Agent. If the user were to press the 'hold'
button, the phone would simply report the key number, and the burden
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RFC 3149 MGCP Business Phone Packages September 2001
of recognizing that this feature key is assigned to the 'hold'
function, and providing such functionality, is left to the Call
Agent.
1.2 Objectives
The high level objectives that were considered in generating the
packages described here are:
- Provide a minimum set of extension packages to the MGCP Version
1.0 protocol to allow applications to take advantage of generic
business phone capabilities.
- Provide event and control extensions at a sufficiently low level
for an application to implement generic business phone functions
without generating excessive or redundant data traffic. (e.g.,
sending feature key information on both press and release would be
a "don't care" for a Call Agent. All it cares about is that the
key was pressed.)
- Provide a mechanism to interface with LCD displays and allow the
flexibility to accommodate a variety of application needs and the
different types of displays available.
2. MGCP Packages for Business Phones
The following packages should be implemented for business phones.
The G,D,L, and H packages are defined in RFC 2705 [1]. Packages KY,
BP and XML are defined in this specification.
______________________________________________________
| Package | Name | Defined |
|______________________________|_________|_____________|
| Generic Media Package | G |in RFC 2705 |
| DTMF package | D |in RFC 2705 |
| Line Package | L |in RFC 2705 |
| Handset Package | H |in RFC 2705 |
| Feature Key Package | KY |in this spec |
| Business Phone Package | BP |in this spec |
| Display XML Package | XML |in this spec |
|______________________________|_________|_____________|
In the tables of events for each package, there are five columns:
Symbol: the unique symbol used for the event
Definition: a short description of the event
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RFC 3149 MGCP Business Phone Packages September 2001
R: an x appears in this column if the event can be requested by the
Call Agent.
S: if nothing appears in this column for an event, then the event
cannot be signalled on command by the Call Agent. Otherwise, the
following symbols identify the type of signal:
OO On/Off signal. The signal is turned on until requested by the
Call Agent to turn it off, and vice versa.
TO Timeout signal. The signal lasts for a given duration unless
it is superseded by a new signal.
BR Brief signal. The event has a short, known duration.
Duration: specifies the duration of TO signals.
2.1 Feature Key Package
Package Name: KY
The Feature Key Package groups events and signals that are associated
with the additional keys that are available on business phones.
____________________________________________________________________
| Symbol | Definition | R | S Duration |
|__________|____________________________|_____|______________________|
| fk1-fk99 | Feature Key | x | |
| ks | Key State | | OO |
| ls | Set Label | | OO |
|__________|____________________________|_____|______________________|
Feature Key (fk1-fk99)
These events map to all the keys on the phone that are not DTMF
keys or locally implemented functions (such as volume). The
mapping of fk number to key is expected to vary between phones.
Note: Some have suggested parameterizing the fk event, i.e.,
sending an RQNT with "R: KY/fk" and an NTFY with "O: KY/fk(1)",
but this is problematic; It is desirable to request only the keys
that can be pressed in a given state, to eliminate the chance that
a mis-pressed button will cancel a timeout signal, as well as to
reduce message traffic. This is not possible within the confines
of MGCP, as requested events cannot be parameterized.
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RFC 3149 MGCP Business Phone Packages September 2001
Key State (ks)
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